Lawyers for the justice secretary told a high court judge in London on Tuesday that the case was being brought “to ensure the POA does not seek to breach the law again”.

The prison officers’ union is banned from taking industrial action under the 1994 Criminal Justice and Public Order Act, which makes it unlawful for “any inducement which leads prison officers to cease to provide services which they would otherwise have done”, Daniel Stilitz QC told Mrs Justice Jay.

He said the justice secretary was concerned that unless the position was determined definitively by the court there would be renewed calls for unlawful industrial action in the future from the union. He claimed the POA had a history of using “inflammatory rhetoric” and engaging in unlawful industrial action despite parliament having “clearly and deliberately” outlawed it.

David Lidington says the POA has a history of engaging in unlawful industrial action. Photograph: Mark Thomas/Rex Shutterstock

The decision to seek an indefinite ban on industrial action by the prison officers follows a ruling in February that the injunction granted then only applied to the precise circumstances at the time despite being worded in general terms.

John Hendy QC, for the union, told the judge that prison officers had only withdrawn from voluntary tasks and not from their contractual obligations: “Prison officers are, as a matter of goodwill, free to decide to volunteer to undertake the tasks. Likewise, once having volunteered they are at liberty to decline to continue to volunteer. The POA denies that the circular constitutes unlawful industrial action.”

Before the two-day hearing got under way, the POA’s general secretary, Steve Gillan, said that regardless of the outcome the union would not be silenced from raising legitimate health and safety concerns and bringing them to the attention of the general public.

“It appears to me when the going gets tough in any negotiations or consultations, senior managers shelter behind the courts rather than have the intelligence to negotiate proper outcomes,” he said.

A Prison Service spokesperson responded: “We fully share the POA objectives to make prisons safe and decent, and where frontline staff are recognised and rewarded for the challenging work they do. But unlawful industrial action is not the way to achieve that aim.

“The secretary of state has met with members of the POA’s national executive committee to discuss the issues facing our prisons. We will continue to maintain a constructive relationship with the POA to ensure the delivery of these reforms.”